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Pinterova‐Leca N, Horsley RR, Danda H, Žídková M, Lhotková E, Šíchová K, Štefková K, Balíková M, Kuchař M, Páleníček T. Naphyrone (naphthylpyrovalerone): Pharmacokinetics, behavioural effects and thermoregulation in Wistar rats. Addict Biol 2021; 26:e12906. [PMID: 32378298 DOI: 10.1111/adb.12906] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 03/11/2020] [Accepted: 03/30/2020] [Indexed: 12/12/2022]
Abstract
Naphthylpyrovalerone (naphyrone) is a pyrovalerone cathinone that potently inhibits monoamine transporters and provides stimulatory-entactogenic effects. Little is known about the safety of naphyrone or its effects in vivo, and more research is needed to acquire knowledge about its fundamental effects on physiology and behaviour. Our objective was to investigate naphyrone's pharmacokinetics, acute toxicity, hyperthermic potential and stimulatory and psychotomimetic properties in vivo in male Wistar rats. Pharmacokinetics after 1 mg/kg subcutaneous (sc.) naphyrone were measured over 6 h in serum, the brain, liver and lungs. Rectal temperature (degree Celsius) was measured over 10 h in group-versus individually housed rats after 20 mg/kg sc. In the behavioural experiments, 5, 10 or 20 mg/kg of naphyrone was administered 15 or 60 min prior to testing. Stimulation was assessed in the open field, and sensorimotor processing in a prepulse inhibition (PPI) task. Peak concentrations of naphyrone in serum and tissue were reached at 30 min, with a long-lasting elevation in the brain/serum ratio, consistent with observations of lasting hyperlocomotion in the open field and modest increases in body temperature. Administration of 20 mg/kg transiently enhanced PPI. Naphyrone crosses the blood-brain barrier rapidly and is eliminated slowly, and its long-lasting effects correspond to its pharmacokinetics. No specific signs of acute toxicity were observed; therefore, clinical care and harm-reduction guidance should be in line with that available for other stimulants and cathinones.
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Affiliation(s)
- Nikola Pinterova‐Leca
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
- Third Faculty of Medicine Charles University in Prague Prague Czech Republic
| | - Rachel R. Horsley
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Hynek Danda
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
- Third Faculty of Medicine Charles University in Prague Prague Czech Republic
| | - Monika Žídková
- Institute of Forensic Medicine and Toxicology, First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Eva Lhotková
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Klára Šíchová
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Kristýna Štefková
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
| | - Marie Balíková
- Institute of Forensic Medicine and Toxicology, First Faculty of Medicine Charles University and General University Hospital in Prague Prague Czech Republic
| | - Martin Kuchař
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
- Forensic Laboratory of Biologically Active Compounds, Department of Chemistry of Natural Compounds University of Chemistry and Technology in Prague Prague Czech Republic
| | - Tomáš Páleníček
- Department of Experimental Neurobiology National Institute of Mental Health Klecany Czech Republic
- Third Faculty of Medicine Charles University in Prague Prague Czech Republic
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Horsley RR, Lhotkova E, Hajkova K, Feriancikova B, Himl M, Kuchar M, Páleníček T. Behavioural, Pharmacokinetic, Metabolic, and Hyperthermic Profile of 3,4-Methylenedioxypyrovalerone (MDPV) in the Wistar Rat. Front Psychiatry 2018; 9:144. [PMID: 29740356 PMCID: PMC5928397 DOI: 10.3389/fpsyt.2018.00144] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 04/03/2018] [Indexed: 01/24/2023] Open
Abstract
3,4-methylenedioxypyrovalerone (MDPV) is a potent pyrovalerone cathinone that is substituted for amphetamines by recreational users. We report a comprehensive and detailed description of the effects of subcutaneous MDPV (1-4 mg/kg) on pharmacokinetics, biodistribution and metabolism, acute effects on thermoregulation under isolated and aggregated conditions, locomotion (open field) and sensory gating (prepulse inhibition, PPI). All studies used male Wistar rats. Pharmacokinetics after single dose of 2 mg/kg MDPV was measured over 6 h in serum, brain and lungs. The biotransformation study recorded 24 h urinary levels of MDPV and its metabolites after 4 mg/kg. The effect of 2 mg/kg and 4 mg/kg on body temperature (°C) was measured over 12 h in group- vs. individually-housed rats. In the open field, locomotion (cm) and its spatial distribution were assessed. In PPI, acoustic startle response (ASR), habituation, and PPI were measured (AVG amplitudes). In behavioural experiments, 1, 2, or 4 mg/kg MDPV was administered 15 or 60 min prior to testing. Thermoregulation and behavioural data were analysed using factorial analysis of variance (ANOVA). Peak concentrations of MDPV in sera, lung and brain tissue were reached in under 30 min. While negligible levels of metabolites were detected in tissues, the major metabolites in urine were demethylenyl-MDPV and demethylenyl-methyl-MDPV at levels three-four times higher than the parent drug. We also established a MDPV brain/serum ratio ~2 lasting for ~120 min, consistent with our behavioural observations of locomotor activation and disrupted spatial distribution of behaviour as well as moderate increases in body temperature (exacerbated in group-housed animals). Finally, 4 mg/kg induced stereotypy in the open field and transiently disrupted PPI. Our findings, along with previous research suggest that MDPV is rapidly absorbed, readily crosses the blood-brain barrier and is excreted primarily as metabolites. MDPV acts as a typical stimulant with modest hyperthermic and psychomimetic properties, consistent with a primarily dopaminergic mechanism of action. Since no specific signs of acute toxicity were observed, even at the highest doses used, clinical care and harm-reduction guidance should be in line with that available for other stimulants and cathinones.
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Affiliation(s)
- Rachel R Horsley
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czechia
| | - Eva Lhotkova
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czechia
| | - Katerina Hajkova
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czechia.,Forensic Laboratory of Biologically Active Compounds, Department of Chemistry of Natural Compounds, University of Chemistry and Technology, Prague, Czechia.,Department of Analytical Chemistry, University of Chemistry and Technology, Prague, Czechia
| | - Barbara Feriancikova
- Forensic Laboratory of Biologically Active Compounds, Department of Chemistry of Natural Compounds, University of Chemistry and Technology, Prague, Czechia
| | - Michal Himl
- Department of Organic Chemistry, University of Chemistry and Technology, Prague, Czechia
| | - Martin Kuchar
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czechia.,Forensic Laboratory of Biologically Active Compounds, Department of Chemistry of Natural Compounds, University of Chemistry and Technology, Prague, Czechia
| | - Tomas Páleníček
- Department of Experimental Neurobiology, National Institute of Mental Health, Klecany, Czechia
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Abstract
Synthetic cathinones are derivatives of the naturally occurring compound cathinone, the main psychoactive ingredient in the khat plant Catha edulis. Cathinone is the β-keto analog of amphetamine, and all synthetic cathinones display a β-keto moiety in their structure. Several synthetic cathinones are widely prescribed medications (e.g., bupropion, Wellbutrin®), while others are problematic drugs of abuse (e.g., 4-methylmethcathinone, mephedrone). Similar to amphetamines, synthetic cathinones are psychomotor stimulants that exert their effects by impairing the normal function of plasma membrane transporters for dopamine (DAT), norepinephrine (NET), and 5-HT (SERT). Ring-substituted cathinones like mephedrone are transporter substrates that evoke neurotransmitter release by reversing the normal direction of transporter flux (i.e., releasers), whereas pyrrolidine-containing cathinones like 3,4-methylenedioxypyrovalerone (MDPV) are potent transporter inhibitors that block neurotransmitter uptake (i.e., blockers). Regardless of molecular mechanism, all synthetic cathinones increase extracellular monoamine concentrations in the brain, thereby enhancing cell-to-cell monoamine signaling. Here, we briefly review the mechanisms of action, structure-activity relationships, and in vivo pharmacology of synthetic cathinones. Overall, the findings show that certain synthetic cathinones are powerful drugs of abuse that could pose significant risk to users.
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Baumann MH, Bukhari MO, Lehner KR, Anizan S, Rice KC, Concheiro M, Huestis MA. Neuropharmacology of 3,4-Methylenedioxypyrovalerone (MDPV), Its Metabolites, and Related Analogs. Curr Top Behav Neurosci 2017; 32:93-117. [PMID: 27830575 PMCID: PMC5392131 DOI: 10.1007/7854_2016_53] [Citation(s) in RCA: 102] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
3,4-Methylenedioxypyrovalerone (MDPV) is a psychoactive component of so-called bath salts products that has caused serious medical consequences in humans. In this chapter, we review the neuropharmacology of MDPV and related analogs, and supplement the discussion with new results from our preclinical experiments. MDPV acts as a potent uptake inhibitor at plasma membrane transporters for dopamine (DAT) and norepinephrine (NET) in nervous tissue. The MDPV formulation in bath salts is a racemic mixture, and the S isomer is much more potent than the R isomer at blocking DAT and producing abuse-related effects. Elevations in brain extracellular dopamine produced by MDPV are likely to underlie its locomotor stimulant and addictive properties. MDPV displays rapid pharmacokinetics when injected into rats (0.5-2.0 mg/kg), with peak plasma concentrations achieved by 10-20 min and declining quickly thereafter. MDPV is metabolized to 3,4-dihydroxypyrovalerone (3,4-catechol-PV) and 4-hydroxy-3-methoxypyrovalerone (4-OH-3-MeO-PV) in vivo, but motor activation produced by the drug is positively correlated with plasma concentrations of parent drug and not its metabolites. 3,4-Catechol-PV is a potent uptake blocker at DAT in vitro but has little activity after administration in vivo. 4-OH-3-MeO-PV is the main MDPV metabolite but is weak at DAT and NET. MDPV analogs, such as α-pyrrolidinovalerophenone (α-PVP), display similar ability to inhibit DAT and increase extracellular dopamine concentrations. Taken together, these findings demonstrate that MDPV and its analogs represent a unique class of transporter inhibitors with a high propensity for abuse and addiction.
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Affiliation(s)
- Michael H Baumann
- Designer Drug Research Unit of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA.
| | - Mohammad O Bukhari
- Designer Drug Research Unit of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
| | - Kurt R Lehner
- Designer Drug Research Unit of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
| | - Sebastien Anizan
- Chemistry and Drug Metabolism Section of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
| | - Kenner C Rice
- Drug Design and Synthesis Section of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
| | - Marta Concheiro
- Chemistry and Drug Metabolism Section of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
- Department of Sciences, John Jay College of Criminal Justice, City University of New York, New York, NY, USA
| | - Marilyn A Huestis
- Chemistry and Drug Metabolism Section of the Intramural Research Program, National Institute on Drug Abuse (NIDA), National Institutes of Health, Baltimore, MD, USA
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Baumann MH, Partilla JS, Lehner KR, Thorndike EB, Hoffman AF, Holy M, Rothman RB, Goldberg SR, Lupica CR, Sitte HH, Brandt SD, Tella SR, Cozzi NV, Schindler CW. Powerful cocaine-like actions of 3,4-methylenedioxypyrovalerone (MDPV), a principal constituent of psychoactive 'bath salts' products. Neuropsychopharmacology 2013; 38:552-62. [PMID: 23072836 PMCID: PMC3572453 DOI: 10.1038/npp.2012.204] [Citation(s) in RCA: 316] [Impact Index Per Article: 28.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The abuse of psychoactive 'bath salts' containing cathinones such as 3,4-methylenedioxypyrovalerone (MDPV) is a growing public health concern, yet little is known about their pharmacology. Here, we evaluated the effects of MDPV and related drugs using molecular, cellular, and whole-animal methods. In vitro transporter assays were performed in rat brain synaptosomes and in cells expressing human transporters, while clearance of endogenous dopamine was measured by fast-scan cyclic voltammetry in mouse striatal slices. Assessments of in vivo neurochemistry, locomotor activity, and cardiovascular parameters were carried out in rats. We found that MDPV blocks uptake of [(3)H]dopamine (IC(50)=4.1 nM) and [(3)H]norepinephrine (IC(50)=26 nM) with high potency but has weak effects on uptake of [(3)H]serotonin (IC(50)=3349 nM). In contrast to other psychoactive cathinones (eg, mephedrone), MDPV is not a transporter substrate. The clearance of endogenous dopamine is inhibited by MDPV and cocaine in a similar manner, but MDPV displays greater potency and efficacy. Consistent with in vitro findings, MDPV (0.1-0.3 mg/kg, intravenous) increases extracellular concentrations of dopamine in the nucleus accumbens. Additionally, MDPV (0.1-3.0 mg/kg, subcutaneous) is at least 10 times more potent than cocaine at producing locomotor activation, tachycardia, and hypertension in rats. Our data show that MDPV is a monoamine transporter blocker with increased potency and selectivity for catecholamines when compared with cocaine. The robust stimulation of dopamine transmission by MDPV predicts serious potential for abuse and may provide a mechanism to explain the adverse effects observed in humans taking high doses of 'bath salts' preparations.
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Affiliation(s)
- Michael H Baumann
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
| | - John S Partilla
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Kurt R Lehner
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Eric B Thorndike
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Alexander F Hoffman
- Electrophysiology Research Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Marion Holy
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Richard B Rothman
- Medicinal Chemistry Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Steven R Goldberg
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Carl R Lupica
- Electrophysiology Research Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
| | - Harald H Sitte
- Center for Physiology and Pharmacology, Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
| | - Simon D Brandt
- School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool, UK
| | - Srihari R Tella
- Drug and Chemical Evaluation Section, Office of Diversion Control, Drug Enforcement Administration, Springfield, VA, USA
| | - Nicholas V Cozzi
- Neuropharmacology Laboratory, Department of Cell and Regenerative Biology, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA
| | - Charles W Schindler
- Preclinical Pharmacology Section of the Intramural Research Program, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD, USA
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Fantegrossi WE, Gannon BM, Zimmerman SM, Rice KC. In vivo effects of abused 'bath salt' constituent 3,4-methylenedioxypyrovalerone (MDPV) in mice: drug discrimination, thermoregulation, and locomotor activity. Neuropsychopharmacology 2013; 38:563-73. [PMID: 23212455 PMCID: PMC3572465 DOI: 10.1038/npp.2012.233] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In recent years, synthetic analogues of naturally occurring cathinone have emerged as psychostimulant-like drugs of abuse in commercial 'bath salt' preparations. 3,4-Methylenedioxypyrovalerone (MDPV) is a common constituent of these illicit products, and its structural similarities to the more well-known drugs of abuse 3,4-methylenedioxymethamphetamine (MDMA), and methamphetamine (METH) suggest that it may have similar in vivo effects to these substances. In these studies, adult male NIH Swiss mice were trained to discriminate 0.3 mg/kg MDPV from saline, and the interoceptive effects of a range of substitution doses of MDPV, MDMA, and METH were then assessed. In separate groups of mice, surgically implanted radiotelemetry probes simultaneously monitored thermoregulatory and locomotor responses to various doses of MDPV and MDMA, as a function of ambient temperature. We found that mice reliably discriminated the MDPV training dose from saline and that cumulative doses of MDPV, MDMA, and METH fully substituted for the MDPV training stimulus. All three drugs had similar ED(50) values in this procedure. Stimulation of motor activity was observed following administration of a wide range of MDPV doses (1-30 mg/kg), and the warm ambient temperature potentiated motor activity and elicited profound stereotypy and self-injurious behavior at 30 mg/kg. In contrast, MDPV-induced hyperthermic effects were observed in only the warm ambient environment. This pattern of effects is in sharp contrast to MDMA, where ambient temperature interacts with thermoregulation, but not locomotor activity. These studies suggest that although the interoceptive effects of MDPV are similar to those of MDMA and METH, direct effects on thermoregulatory processes and locomotor activity are likely mediated by different mechanisms than those of MDMA.
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Affiliation(s)
- William E Fantegrossi
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
| | - Brenda M Gannon
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Sarah M Zimmerman
- Department of Pharmacology and Toxicology, College of Medicine, University of Arkansas for Medical Sciences, Little Rock, AR, USA
| | - Kenner C Rice
- Drug Design and Synthesis Section, Chemical Biology Research Branch, NIDA and NIAAA, Bethesda, MD, USA
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Gruner JA, Marcy VR, Lin YG, Bozyczko-Coyne D, Marino MJ, Gasior M. The roles of dopamine transport inhibition and dopamine release facilitation in wake enhancement and rebound hypersomnolence induced by dopaminergic agents. Sleep 2010; 32:1425-38. [PMID: 19928382 DOI: 10.1093/sleep/32.11.1425] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
STUDY OBJECTIVE Rebound hypersomnolence (RHS: increased sleep following increased wake) is a limiting side-effect of many wake-promoting agents. In particular, RHS in the first few hours following wake appears to be associated with dopamine (DA)-releasing agents, e.g., amphetamine, but whether it can also be produced by DA transporter (DAT) inhibition alone is unknown. In these studies, DA-releasing and DAT-inhibiting agents and their interaction were systematically examined for their ability to increase wake and induce RHS. DESIGN Chronically implanted rats were evaluated in a blinded, pseudo-randomized design. PARTICIPANTS 237 rats were used in these studies with 1 week between repeat tests. INTERVENTIONS Animals were habituated overnight and dosed the next day, 5 h after lights on, with test agents. MEASUREMENTS AND RESULTS Sleep/wake activityand RHS were evaluated using EEG/EMG recording up to 22 h post dosing. In vitro dopamine release was evaluated in rat synaptosomes. At doses that produced equal increases in wake, DA-releasing (amphetamine, methamphetamine, phentermine) and several DAT-inhibiting agents (cocaine, bupropion, and methylphenidate) produced RHS during the first few hours after the onset of sleep recovery. However, other DAT-inhibiting agents (mazindol, nomifensine, GBR-12909, and GBR-12935) did not produce RHS. Combination treatment with amphetamine and nomifensine produced waking activity greater than the sum of their individual activities alone while ameliorating the amphetamine-like RHS. In rat synaptosomes, nomifensine reduced the potency of amphetamine to induce DA release approximately 270-fold, potentially explaining its action in ameliorating amphetamine-induced RHS. CONCLUSIONS All DA releasing agents tested, and some DAT-inhibiting agents, produced RHS at equal wake-promoting doses. Thus amphetamine-like DA release appears sufficient for inducing RHS, but additional properties (pharmacologic and/or pharmacokinetic) evidently underlie RHS of other DAT inhibitors. Enhancing wake while mitigating RHS can be achieved by combining DAT-inhibiting and DA-releasing agents.
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Hiranita T, Soto PL, Newman AH, Katz JL. Assessment of reinforcing effects of benztropine analogs and their effects on cocaine self-administration in rats: comparisons with monoamine uptake inhibitors. J Pharmacol Exp Ther 2009; 329:677-86. [PMID: 19228996 DOI: 10.1124/jpet.108.145813] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Benztropine (BZT) analogs inhibit dopamine uptake but are less effective than cocaine in producing behavioral effects predicting abuse liability. The present study compared reinforcing effects of intravenous BZT analogs with those of standard monoamine uptake inhibitors and the effects of their oral pretreatment on cocaine self-administration. Responding of rats was maintained by cocaine [0.032-1.0 mg/kg/injection (inj)] or food reinforcement under fixed-ratio five-response schedules. Maximal rates of responding were maintained by 0.32 mg/kg/inj cocaine or substituted methylphenidate, with lower rates maintained at lower and higher doses. The N-methyl BZT analog, AHN 1-055 (3alpha-[bis(4'-fluorophenyl)methoxy]-tropane), also maintained responding (0.1 mg/kg/inj), although maximal rates were less than those with cocaine. Responding was not maintained above vehicle levels by the N-allyl, AHN 2-005 (N-allyl-3alpha-[bis(4'-fluorophenyl)methoxy]-tropane), and N-butyl, JHW 007 [N-(n-butyl)-3alpha-[bis(4'-fluorophenyl)methoxy]-tropane], BZT analogs, and it was not maintained with nisoxetine or citalopram. Presession treatment with methylphenidate (3.2-32 mg/kg) dose-dependently shifted the cocaine self-administration dose-effect curve leftward, whereas nisoxetine and citalopram effects were not significant. An intermediate dose of AHN 1-055 (32 mg/kg) increased responding maintained by low cocaine doses and decreased responding maintained by higher doses. A higher dose of AHN 1-055 completely suppressed cocaine-maintained responding. Both AHN 2-005 and JHW 007 dose-dependently (10-32 mg/kg) decreased cocaine self-administration, shifting its dose-effect curve down. Decreases in cocaine-maintained responding occurred at doses of methylphenidate and BZT analogs that left food-maintained responding unchanged. During a component in which injections were not available, methylphenidate and AHN 1-055, but not AHN 2-005 or JHW 007, increased response rates. These findings further support the low abuse liability of BZT analogs and their potential development as medications for cocaine abuse.
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Affiliation(s)
- Takato Hiranita
- Psychobiology Section, Medications Discovery Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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Atypical Dopamine Uptake Inhibitors that Provide Clues About Cocaine's Mechanism at the Dopamine Transporter. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/7355_2008_027] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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10
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Kimmel HL, Negus SS, Wilcox KM, Ewing SB, Stehouwer J, Goodman MM, Votaw JR, Mello NK, Carroll FI, Howell LL. Relationship between rate of drug uptake in brain and behavioral pharmacology of monoamine transporter inhibitors in rhesus monkeys. Pharmacol Biochem Behav 2008; 90:453-62. [PMID: 18468667 DOI: 10.1016/j.pbb.2008.03.032] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2008] [Revised: 03/11/2008] [Accepted: 03/29/2008] [Indexed: 10/22/2022]
Abstract
Although inhibition of dopamine transporters (DAT) and the subsequent increase in dopamine clearly play a role in the effects of psychomotor stimulants, the reinforcing effectiveness of DAT inhibitors varies. Previous studies suggest that pharmacokinetic and pharmacodynamic properties of these drugs account for this variability. The present studies compared the time course and behavioral effects of five phenyltropane analogs of cocaine with high affinity for DAT and varying time courses of action in rhesus monkeys. The rate of drug uptake in putamen was measured using positron emission tomography neuroimaging. The rank order of the time to peak drug uptake was cocaine<RTI-336<RTI-150<RTI-113<RTI-177. Cocaine and all five analogs fully substituted for the cocaine cue in animals trained to discriminate cocaine from saline. All of the drugs were self-administered under a progressive-ratio schedule of drug self-administration and reinstated previously extinguished self-administration maintained under a second-order schedule. The time to peak drug uptake corresponded closely with the time to peak discriminative stimulus effects, and there was a trend for the time of peak drug uptake to correspond negatively with the peak number of drug infusions. Collectively, these results indicate that the rate of drug entry in brain can play an important role in the behavioral pharmacology of psychomotor stimulants.
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Affiliation(s)
- Heather L Kimmel
- Yerkes National Primate Research Center, Emory University, Atlanta, GA 30322, USA.
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11
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Kimmel HL, O'Connor JA, Carroll FI, Howell LL. Faster onset and dopamine transporter selectivity predict stimulant and reinforcing effects of cocaine analogs in squirrel monkeys. Pharmacol Biochem Behav 2007; 86:45-54. [PMID: 17258302 PMCID: PMC1850383 DOI: 10.1016/j.pbb.2006.12.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2006] [Revised: 12/12/2006] [Accepted: 12/13/2006] [Indexed: 11/16/2022]
Abstract
Although the behavioral-stimulant and reinforcing effects of cocaine and related psychomotor stimulants have been attributed to their actions at the dopamine transporter (DAT), the reinforcing effectiveness of these compounds varies. The properties that confer these differences are important considerations when developing agonist pharmacotherapies for the treatment of stimulant abuse. The present studies focused on the time course of action and pharmacological specificity of six 3-phenyltropane analogs of cocaine (RTI-112, RTI-126, RTI-150, RTI-171, RTI-177, and RTI-336) by observing their behavioral-stimulant, neurochemical, and reinforcing effects in squirrel monkeys. The faster-onset analogs (RTI-126, RTI-150, and RTI-336), and one of the slower-onset DAT selective analogs (RTI-177 and RTI-171) produced behavioral-stimulant effects, while the slower-onset nonselective analog RTI-112 did not. The time to the peak behavioral-stimulant effect and the peak caudate dopamine levels was strongly correlated, but the area under the curve of the time course of behavioral-stimulant effect and dopamine levels was not correlated. These results suggest that the rate of onset plays a more important role than duration of action in the stimulant effect of these analogs. In addition, the slower-onset nonselective analog (RTI-112) clearly did not exhibit any reinforcing effects while the faster-onset nonselective (RTI-126) and all the DAT-selective analogs showed robust reinforcing effects (RTI-150, and RTI-177) or showed trends towards reinforcing effects (RTI-336 and RTI-171). Hence, there was a general trend for compounds that had a faster onset and/or DAT selectivity to produce significant behavioral-stimulant and reinforcing effects.
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Affiliation(s)
- Heather L Kimmel
- Division of Neuroscience, Yerkes National Primate Research Center, Emory University, Atlanta, GA 30329, United States.
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12
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Meltzer PC, Butler D, Deschamps JR, Madras BK. 1-(4-Methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one (Pyrovalerone) analogues: a promising class of monoamine uptake inhibitors. J Med Chem 2006; 49:1420-32. [PMID: 16480278 PMCID: PMC2602954 DOI: 10.1021/jm050797a] [Citation(s) in RCA: 266] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Dopamine, serotonin, and norepinephrine are essential for neurotransmission in the mammalian system. These three neurotransmitters have been the focus of considerable research because the modulation of their production and their interaction at monoamine receptors has profound effects upon a multitude of pharmacological outcomes. Our interest has focused on neurotransmitter reuptake mechanisms in a search for medications for cocaine abuse. Herein we describe the synthesis and biological evaluation of an array of 2-aminopentanophenones. This array has yielded selective inhibitors of the dopamine and norepinephrine transporters with little effect upon serotonin trafficking. A subset of compounds had no significant affinity at 5HT1A, 5HT1B, 5HT1C, D1, D2, or D3 receptors. The lead compound, racemic 1-(4-methylphenyl)-2-pyrrolidin-1-yl-pentan-1-one 4a, was resolved into its enantiomers and the S isomer was found to be the most biologically active enantiomer. Among the most potent of these DAT/NET selective compounds are the 1-(3,4-dichlorophenyl)- (4u) and the 1-naphthyl- (4t) 2-pyrrolidin-1-yl-pentan-1-one analogues.
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Affiliation(s)
- Peter C Meltzer
- Organix Inc., 240 Salem Street, Woburn, Massachusetts 01801, USA.
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13
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Desai RI, Kopajtic TA, Koffarnus M, Newman AH, Katz JL. Identification of a dopamine transporter ligand that blocks the stimulant effects of cocaine. J Neurosci 2005; 25:1889-93. [PMID: 15728828 PMCID: PMC6726049 DOI: 10.1523/jneurosci.4778-04.2005] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
There is a large unmet medical need for cocaine addiction treatments. Studies have indicated that the dopamine transporter (DAT) is the primary biological target of cocaine, and most drugs that have DAT affinity have behavioral effects like those of cocaine. However, analogs of benztropine have high DAT affinity and behavioral effects that show varying degrees of similarity to cocaine. We now report the discovery that a benztropine analog, JHW007, with high affinity for the DAT does not have cocaine-like behavioral effects and antagonizes the effects of cocaine. JHW007 occupied the DAT in vivo more slowly than did cocaine and had not reached an apparent plateau up to 270 min after injection. The in vivo binding of cocaine to the DAT suggested rate of DAT occupancy as an important contributor to its behavioral effects, and the slow association with the DAT may provide an explanation for JHW007 being relatively devoid of cocaine-like behavioral effects. The antagonism of cocaine suggests that DAT ligands with reduced cocaine-like activity can function as cocaine antagonists and suggests JHW007 as a lead for discovery of cocaine-abuse pharmacotherapeutics.
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Affiliation(s)
- Rajeev I Desai
- Psychobiology, Medications Discovery Research Branch, National Institute on Drug Abuse, Intramural Research Program, Department of Health and Human Services, National Institutes of Health, Baltimore, Maryland 21224, USA
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14
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Desai RI, Kopajtic TA, French D, Newman AH, Katz JL. Relationship between in Vivo Occupancy at the Dopamine Transporter and Behavioral Effects of Cocaine, GBR 12909 [1-{2-[Bis-(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)piperazine], and Benztropine Analogs. J Pharmacol Exp Ther 2005; 315:397-404. [PMID: 16014753 DOI: 10.1124/jpet.105.091231] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Analogs of benztropine (BZT) bind to the dopamine (DA) transporter and inhibit DA uptake but often have behavioral effects that differ from those of cocaine and other DA-uptake inhibitors. To better understand these differences, we examined the relationship between locomotor-stimulant effects of cocaine, 1-{2-[bis-(4-fluorophenyl)methoxy]ethyl}-4-(3-phenylpropyl)-piperazine (GBR 12909), and BZT analogs [(3alpha-[bis(4'-fluorophenyl)methoxy]-tropane) (AHN 1-055) and (N-allyl-3alpha-[bis(4'-fluorophenyl)methoxy]-tropane) (AHN 2-005)] and their in vivo displacement of the DA transporter ligand [125I]3beta-(4-iodophenyl)-tropan-2beta-carboxylic acid isopropyl ester hydrochloride (RTI-121) in striatum. Cocaine, GBR 12909, and BZT analogs each displaced [125I]RTI-121 and stimulated locomotor activity in a dose- and time-dependent manner. The time course revealed a slower onset of both effects for AHN 1-055 and AHN 2-005 compared with cocaine and GBR 12909. The BZT analogs were less effective than cocaine and GBR 12909 in stimulating locomotor activity. Locomotor stimulant effects of cocaine were generally greater than predicted by the regression of displacement of [125I]RTI-121 and effect at short times after injection and less than predicted at longer times after injection. This result suggests that the apparent rate of occupancy of the DA transporter, in addition to percentage of sites occupied, contributes to the behavioral effects of cocaine. The present results suggest that among drugs that act at the DA transporter, the slower apparent rates of occupancy with the DA transporter by the BZT analogs may contribute in an important way to differences in their effectiveness.
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Affiliation(s)
- Rajeev I Desai
- Medication Discovery Research Branch, National Institute on Drug Abuse, Intramural Research Program, National Institutes of Health, Baltimore, MD 21224, USA
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15
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Sakamuri S, Enyedy IJ, Zaman WA, Tella SR, Kozikowski AP, Flippen-Anderson JL, Farkas T, Johnson KM, Wang S. 2,3-Disubstituted quinuclidines as a novel class of dopamine transporter inhibitors. Bioorg Med Chem 2003; 11:1123-36. [PMID: 12614900 DOI: 10.1016/s0968-0896(02)00450-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
There is considerable interest in developing dopamine transporter (DAT) inhibitors as potential therapies for the treatment of cocaine abuse. We report herein our pharmacophore-based discovery and molecular modeling-assisted rational design of 2,3-disubstituted quinuclidines as potent DAT inhibitors with a novel chemical scaffold. Through 3-D-database pharmacophore searching, compound 12 was identified as a very weak DAT inhibitor with K(i) values of 7.3 and 8.9 microM in [3H]mazindol binding and in inhibition of dopamine reuptake, respectively. Molecular modeling-assisted rational design and chemical modifications led to identification of potent analogues (-)-29 and 34 with K(i) values of 14 and 32 nM for both compounds in binding affinity and inhibition of dopamine reuptake, respectively. Behavioral pharmacological evaluations in rodents showed that 34 has a profile very different from cocaine. While 34 is substantially more potent than cocaine as a DAT inhibitor, it is approximately four times less potent than cocaine in mimicking the discriminative stimulus properties of cocaine in rat. On the other hand, 34 (3-30 mg/kg) lacks either the locomotor stimulant or stereotypic properties of cocaine in mice. Importantly, 34 blocks locomotor stimulant activity induced by 20 mg/kg cocaine in mice, with an estimated ED(50) of 19 mg/kg. Taken together, our data suggest that 34 represents a class of potent DAT inhibitors with a novel chemical scaffold and a behavioral pharmacological profile different from that of cocaine in rodents. Thus, 34 may serve as a novel lead compound in the ultimate development of therapeutic entities for cocaine abuse and/or addiction.
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Affiliation(s)
- Sukumar Sakamuri
- Department of Neurology, Georgetown University Medical Center, 3900 Reservoir Rd., Washington, DC 20007, USA
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16
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Drouin C, Blanc G, Villégier AS, Glowinski J, Tassin JP. Critical role of alpha1-adrenergic receptors in acute and sensitized locomotor effects of D-amphetamine, cocaine, and GBR 12783: influence of preexposure conditions and pharmacological characteristics. Synapse 2002; 43:51-61. [PMID: 11746733 DOI: 10.1002/syn.10023] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Psychostimulant-induced locomotor hyperactivity is commonly associated with an inhibition of dopamine reuptake. However, a physiological coupling between noradrenergic and dopaminergic neurons occurring through the stimulation of alpha1-adrenergic receptors has recently been proposed. This possibility was tested on locomotor responses induced either by D-amphetamine and cocaine, which both interfere with noradrenergic and dopaminergic transmissions, or by GBR 12783, a specific dopamine reuptake inhibitor. In an attempt to control the effects of stress and novelty on noradrenergic neurons activity, rats were submitted to habituation procedures consisting of either a 15-h period of habituation to the experimental environment ("long-habituation") or to repeated exposure to intraperitoneal saline injections for 3 consecutive days ("three-session"). Three-session-exposed animals exhibited a pronounced locomotor reactivity to saline injection which did not occur after noradrenergic depletion, clonidine (20 microg/kg) or prazosin (0.5 mg/kg) pretreatments, or in long-habituation-preexposed animals. Cocaine and GBR 12783 locomotor hyperactivities were doubled in three-session vs. long-habituation-preexposed rats, whereas D-amphetamine responses were similar in both conditions. Prazosin (0.5 mg/kg) pretreatment reduced the acute locomotor effects of the three psychostimulants in both procedures and blocked the behavioral sensitization induced by repeated injections of D-amphetamine (0.75 mg/kg) or cocaine (5 mg/kg). GBR 12783 (5 mg/kg) failed to induce significant behavioral sensitization. In addition to their role in the acute and sensitized locomotor responses to psychostimulants possessing different pharmacological characteristics, alpha1-adrenergic receptors are involved in animal reactivity to previously experimented procedures. This suggests an implication of noradrenergic neurons in the vulnerability to psychostimulants.
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Affiliation(s)
- Candice Drouin
- Chaire de Neuropharmacologie, INSERM U114, Collège de France, 75005 Paris, France
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17
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El Yacoubi M, Ledent C, Parmentier M, Costentin J, Vaugeois J. SCH 58261 and ZM 241385 differentially prevent the motor effects of CGS 21680 in mice: evidence for a functional 'atypical' adenosine A(2A) receptor. Eur J Pharmacol 2000; 401:63-77. [PMID: 10915839 DOI: 10.1016/s0014-2999(00)00399-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The acute motor effects elicited by drugs acting upon adenosine A(2A) receptors, namely the highly selective agonist CGS 21680 or the antagonists SCH 58261 and ZM 241385, were investigated in mice. CGS 21680 dose-dependently (0.1-2.5 mg/kg i.p.) decreased horizontal and vertical motor activities. The depressant effect of CGS 21680 (0. 5 mg/kg i.p.) was maintained in mice pretreated by the adenosine receptor antagonist 8-(p-sulfophenyl)-theophylline (10-30 mg/kg i.p. ), which poorly penetrates the blood-brain barrier, but was completely lost in adenosine A(2A) receptor knockout mice. Thus, the adenosine A(2A) receptor is critically involved in motor activity. SCH 58261 (1-10 mg/kg i.p.) increased locomotion and rearing with a quick onset, but for a shorter period in mice habituated to the environment than in mice unfamiliar to it. ZM 241385 (7.5-60 mg/kg i. p.) stimulated horizontal and vertical activities with a slow onset at the two highest tested doses, similarly in naive and in habituated mice. The increase in locomotion elicited by ZM 241385 (15-30 mg/kg i.p. and 10-20 nM i.c.v.) was retained in mice treated by CGS 21680 (0.5 mg/kg i.p.) but that elicited by SCH 58261 (1-3-10 mg/kg i.p. and 10-20 nM i.c.v.) partially subsided. In conclusion, both 'striatal-like'/'SCH 58261-sensitive' adenosine A(2A) receptors and 'ZM 241385-sensitive'/'atypical' CGS 21680 binding sites may mediate CGS 21680-induced motor effects. Moreover, our results suggest that 'atypical' CGS 21680 binding sites could be adenosine A(2A) receptors with a peculiar pharmacological profile.
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Affiliation(s)
- M El Yacoubi
- UPRESA CNRS 6036, IFRMP 23, U.F.R. de Médecine and Pharmacie, 22 Boulevard Gambetta, 76183 Cédex, Rouen, France
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18
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Carroll FI, Howell LL, Kuhar MJ. Pharmacotherapies for treatment of cocaine abuse: preclinical aspects. J Med Chem 1999; 42:2721-36. [PMID: 10425082 DOI: 10.1021/jm9706729] [Citation(s) in RCA: 168] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F I Carroll
- Chemistry and Life Sciences, Research Triangle Institute, Research Triangle Park, North Carolina 27709, USA
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19
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Vaugeois JM, Corera AT, Deslandes A, Costentin J. Although chemically related to amineptine, the antidepressant tianeptine is not a dopamine uptake inhibitor. Pharmacol Biochem Behav 1999; 63:285-90. [PMID: 10371658 DOI: 10.1016/s0091-3057(98)00242-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
We investigated whether the antidepressant tianeptine shares the dopamine uptake inhibitory properties of the chemically related antidepressant amineptine. Tianeptine dose dependently (5, 10, 20, 40 mg/kg IP) increased locomotor activity in mice. This stimulant effect (20 mg/kg IP) was dose dependently prevented not only by the D1 dopamine receptor antagonist SCH 23390 (7.5. 15, 30 microg/kg SC), but also by the D2 dopamine receptor antagonist haloperidol (50, 100, 200 microg/kg IP), in contrast to that elicited by dopamine uptake inhibitors. Where the latter prevent dexamphetamine-induced (3 mg/kg SC) reversion of akinesia in mice pretreated with reserpine (4 mg/kg SC, 5 h before test), tianeptine (20 mg/kg IP, 30 min before test) did not. Tested up to a concentration of 10-4 M, tianeptine did neither inhibit the [3H]dopamine uptake into mouse striatal synaptosomes nor compete in vitro with the specific binding of [3H]WIN 35,428 at dopamine transporters from striatal membranes. Finally, in mice injected IV with a tracer dose of [3H]WIN 35,428 (1 microCi), the highest tested dose of tianeptine (40 mg/kg IP) did not reduce the specific binding of the radioligand to striatal dopamine transporters. It is concluded that the antidepressant effect of tianeptine does not depend upon a blockade of the neuronal dopamine transporter.
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Affiliation(s)
- J M Vaugeois
- Unité de Neuropsychopharmacologie Expérimentale, UPRES-A 6036 CNRS, IFRMP, UFR de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France
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20
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Garcia de Mateos-Verchere J, Vaugeois JM, Naudin B, Costentin J. Behavioural and neurochemical evidence that the antimicrobial agent oxolinic acid is a dopamine uptake inhibitor. Eur Neuropsychopharmacol 1998; 8:255-9. [PMID: 9928913 DOI: 10.1016/s0924-977x(97)00083-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The antimicrobial agent oxolinic acid, injected i.p. in mice, induced a dose dependent increase in locomotor activity. This stimulation culminated at the 32 mg/kg dose and became smaller for higher doses (64-128 mg/kg). When opposed to increasing doses (50-100-200 microg/kg i.p.) of haloperidol (D2 dopamine receptor antagonist), the stimulant locomotor effect of 32 mg/kg oxolinic acid was not significantly reversed. On the contrary increasing doses (7.5-15-30 microg/kg s.c.) of SCH 23390 (D1 dopamine receptor antagonist) inhibited the stimulant locomotor effect. In mice made completely akinetic by a pretreatment with reserpine (4 mg/kg s.c., 18 h before testing), dexamphetamine (2 mg/kg s.c.) reversed this akinesia and even displayed a stimulant activity, similar to that observed in mice not treated by reserpine. On the contrary, oxolinic acid (32 mg/kg) did not reverse the reserpine induced akinesia and even opposed the reversion induced by dexamphetamine. In a synaptosomal fraction prepared from striatum of rats, oxolinic acid inhibited the 3H dopamine uptake with an IC50 = 4.3+/-0.6 x 10(-6) M. Finally, in mice injected i.v. with a tracer dose of 3H WIN 35428 (1 microCi) (a dopamine uptake blocker), 32 mg/kg oxolinic acid, i.p. administered, reduced by about 50% the specific binding of the radioligand to striatal dopamine carriers. It is concluded that the stimulant locomotor effect of oxolinic acid depends on the blockade of the neuronal dopamine uptake complex.
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Affiliation(s)
- J Garcia de Mateos-Verchere
- IFRMP-Unité de Neuropsychopharmacologie, UPRESA 6036, C.N.R.S., Faculté de Médecine et Pharmacie de Rouen, Saint Etienne du Rouvray, France
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21
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Cook CD, Carroll FI, Beardsley PM. Separation of the locomotor stimulant and discriminative stimulus effects of cocaine by its C-2 phenyl ester analog, RTI-15. Drug Alcohol Depend 1998; 50:123-8. [PMID: 9649963 DOI: 10.1016/s0376-8716(98)00004-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
During a routine evaluation of several analogs of cocaine, we observed that the C-2 phenyl ester, RTI-15, appeared to suppress motor activity in rats. We subsequently examined RTI-15 for its cocaine-like stimulus effects as well as for its locomotor activity effects. RTI-15 dose-dependently generalized from the cocaine stimulus in rats trained to discriminate 10 mg/kg cocaine from saline with complete substitution (> or = 80% cocaine-lever responding) occurring at 24 mg/kg. During automated locomotor activity tests in mice, cocaine (3-60 mg/kg) dose-dependently increased activity counts and movement time across the entire 1 h test session. RTI-15, however, had little affect on activity counts and movement time from 10-30 mg/kg, and decreased these measures at 60 mg/kg, the highest dose tested. These results indicate that while changing the C-2 methyl ester of cocaine to a C-2 phenyl ester increases dopamine-transporter selectivity, it dissociates its locomotor activity effects from its discriminative stimulus effects suggesting that the underlying mechanisms mediating these effects are not identical.
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Affiliation(s)
- C D Cook
- Department of Psychology, University of North Carolina, Chapel Hill 27599-3270, USA
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22
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Katz JL, Newman AH, Izenwasser S. Relations between heterogeneity of dopamine transporter binding and function and the behavioral pharmacology of cocaine. Pharmacol Biochem Behav 1997; 57:505-12. [PMID: 9218275 DOI: 10.1016/s0091-3057(96)00441-8] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Both in vitro binding studies and studies of dopamine uptake have indicated that there is a heterogeneity of action of cocaine and cocaine analogs. Both high- and low-affinity binding sites have been identified. Some drugs that bind to the dopamine transporter show both high- and low-affinity components whereas others do not. Behavioral studies have indicated that the high-affinity component appears to be the one most directly involved in the actions of cocaine related to abuse. These conclusions are based on correlations of affinities and psychomotor stimulant effects. In addition, tolerance to the psychomotor stimulant effects of cocaine occurs with a concomitant change in only the high-affinity component for dopamine uptake. Certain dopamine uptake inhibitors may have only actions mediated by the low-affinity component. These drugs bind to the dopamine transporter and inhibit dopamine uptake; however, they do not have behavioral effects like those of cocaine. This finding is a critical point of inquiry for the dopamine hypothesis because, based on the neurochemical data, these drugs should have behavioral actions like those of cocaine. In contrast, some of these drugs antagonize the behavioral effects of cocaine, suggesting that the low-affinity site somehow modulates the actions mediated by the high-affinity site. Recently, some benztropine analogs have been discovered that bind to the dopamine transporter and inhibit dopamine uptake monophasically but have behavioral effects that are dissimilar to those of cocaine. These compounds may prove useful in determining the behavioral significance of heterogeneity of actions at the dopamine transporter. Further, these studies may provide leads to novel therapeutics for the treatment of cocaine abuse.
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Affiliation(s)
- J L Katz
- Psychobiology Section, NIDA Addiction Research Center, National Institutes of Health, Baltimore, MD 21224, USA
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23
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Gatley SJ, Volkow ND, Gifford AN, Ding YS, Logan J, Wang GJ. Model for estimating dopamine transporter occupancy and subsequent increases in synaptic dopamine using positron emission tomography and carbon-11-labeled cocaine. Biochem Pharmacol 1997; 53:43-52. [PMID: 8960062 DOI: 10.1016/s0006-2952(96)00655-7] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Although increases in dopamine secondary to the inhibition of the dopamine transporter appear to underlie the reinforcing properties of cocaine, there is presently no model that relates the elevation of synaptic dopamine to the transporter occupancy by cocaine. We propose such a model based on positron emission tomographic (PET) measurements of the brain concentration of cocaine and the assumption of rapid equilibrium between free cocaine and cocaine bound to the dopamine transporter. A euphorigenic dose of cocaine (about 40 mg) is predicted to occupy 80-90% of the transporters, while a perceptible dose (about 5 mg) occupies about 40% of the transporters. If reuptake of dopamine is reduced in proportion to the fraction of transporters occupied by cocaine, our model indicates that synaptic dopamine rises supra-linearly with occupancy, so that 5 and 40 mg doses of cocaine give about 2- and 10-fold increases, respectively. A consequence is that a given dose of cocaine produces a similar degree of elevation of dopamine regardless of the prior level of occupation of the transporters by cocaine. This prediction is supported by recent PET/neuropsychological studies in our laboratory where dopamine transporter occupancy was measured after giving methylphenidate intravenously to volunteers; similarly intense "highs" were reported whether the initial occupancy was zero or 75-85%. It could also explain why attempts to block the psychostimulant-induced "high" by pretreating subjects with drugs that block the dopamine transporter have been unsuccessful, and why the use of methylphenidate to treat cocaine addicts led to increased cocaine consumption.
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Affiliation(s)
- S J Gatley
- Medical Department, Brookhaven National Laboratory, Upton, NY 11973, USA
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24
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Lee FJ, Pristupa ZB, Ciliax BJ, Levey AI, Niznik HB. The dopamine transporter carboxyl-terminal tail. Truncation/substitution mutants selectively confer high affinity dopamine uptake while attenuating recognition of the ligand binding domain. J Biol Chem 1996; 271:20885-94. [PMID: 8702845 DOI: 10.1074/jbc.271.34.20885] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In order to delineate structural motifs regulating substrate affinity and recognition for the human dopamine transporter (DAT), we assessed [3H]dopamine uptake kinetics and [3H]CFT binding characteristics of COS-7 cells transiently expressing mutant DATs in which the COOH terminus was truncated or substituted. Complete truncation of the carboxyl tail from Ser582 allowed for the expression of biphasic [3H]dopamine uptake kinetics displaying both a low capacity (Vmax approximately 0.4 pmol/10(5) cells/min) high affinity (Km approximately 300 nM) component and one exhibiting low affinity (Km approximately 15 microM] and high capacity (Vmax approximately 5 pmol/10(5)cells/min) with a concomitant 40% decrease in overall apparent Vmax relative to wild type (WT) DAT. Truncation of the last 22 amino acids or substitution of the DAT-COOH tail with sequences encoding the intracellular carboxyl-terminal of either dopamine D1 or D5 receptors produced results that were identical to those with the fully truncated DAT, suggesting that the induction of biphasic dopamine uptake kinetics is likely conferred by removal of DAT-specific sequence motifs distal to Pro597. The attenuation of WT transport activity, either by lowering levels of DAT expression or by pretreatment of cells with phorbol 12-myristate 13-acetate (1 microM), did not affect the kinetics of [3H]dopamine transport. The estimated affinity of dopamine (Ki approximately 180 nM) for all truncated/substituted DAT mutants was 10-fold lower than that of WT DAT (approximately 2000 nM) and appears selective for the endogenous substrate, since the estimated inhibitory constants for numerous putative substrates or uptake inhibitors were virtually identical to those obtained for WT DATs. In marked contrast, DAT truncation/substitution mutants displayed significantly reduced high affinity [3H]CFT binding interactions with estimated Ki values for dopamine and numerous other substrates and inhibitors tested from 10-100-fold lower than that observed for WT DAT. Moreover, co-expression of truncated and/or substituted DATs with WT transporter failed to reconstitute functional or pharmacological activities associated with both transporters. Instead, complete restoration of uniphasic low affinity [3H]dopamine uptake kinetics (Km approximately 2000 nM) and high affinity substrate and inhibitor [3H]CFT binding interactions attributable to WT DATs were evident. These data clearly suggest the functional independence and differential regulation of the dopamine translocation process from the characteristics exhibited by its ligand binding domain. The lack of functional phenotypic expression of mutant DAT activities in cells co-expressing WT transporter is consistent with the contention that native DATs may exist as multisubunit complexes, the formation and maintenance of which is dependent upon sequences encoded within the carboxyl tail.
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Affiliation(s)
- F J Lee
- Department of Pharmacology, University of Toronto, Toronto, Ontario M5S 1A8, Canada
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25
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Karoum F, Chrapusta SJ, Brinjak R, Hitri A, Wyatt RJ. Regional effects of amphetamine, cocaine, nomifensine and GBR 12909 on the dynamics of dopamine release and metabolism in the rat brain. Br J Pharmacol 1994; 113:1391-9. [PMID: 7889297 PMCID: PMC1510507 DOI: 10.1111/j.1476-5381.1994.tb17152.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
1. The effects of single-dose regimens of amphetamine, cocaine, nomifensine and GBR 12909 on the dynamics of dopamine (DA) release and metabolism were evaluated in the frontal cortex, hypothalamus, nucleus accumbens and striatum. The regimens selected are known to produce substantial behavioural effects. 2. 3-Methoxytyramine (3MT) and 3,4-dihydroxyphenylacetic acid (DOPAC) rates of formation were used to assess DA metabolism by catechol-O-methyltransferase and monoamine oxidase respectively. The rate of formation of 3MT was used as an index of synaptic DA. The ratio and sum, respectively, of 3MT and DOPAC rates of formation were used to assess DA reuptake inhibition and turnover. 3. The effects of amphetamine on 3MT production and DOPAC steady-state levels were similar in all regions, suggesting similar pharmacodynamic actions. Amphetamine increased 3MT formation and steady-state levels, and reduced DOPAC steady-state levels. DOPAC formation was significantly reduced only in the nucleus accumbens and striatum. Total DA turnover remained unchanged except in the nucleus accumbens. Apparently, the amphetamine-induced increase in DA release occurred at the expense of intraneuronal DA metabolism and did not require stimulation of synthesis. 4. Nomifensine elevated 3MT formation in all regions. A similar effect was produced by cocaine except in the nucleus accumbens. GBR 12909 elevated 3MT production only in the hypothalamus, the striatum and the nucleus accumbens. 5. Cocaine selectively reduced DOPAC formation in the frontal cortex. Nomifensine increased and reduced, respectively, DOPAC formation in striatum and hypothalamus. GBR 12909 elevated DOPAC formation in all regions except the cortex, where pargyline did not reduce DOPAC levels in GBR 12909-treated rats. 6. Ratios and sum of 3MT and DOPAC rates of formation also exhibited wide regional variations for each drug. In contrast to the other drugs, the ratio was not increased after GBR 12909. Apparently, the DA uptake properties of this drug are poorly related to its in vivo effects on the ratio of 3MTproduction to that of DOPAC, which should increase when DA reuptake is inhibited.7. Total DA turnover was increased by GBR 12909 in the hypothalamus, nucleus accumbens and striatum, while cocaine and nomifensine increased it only in the nucleus accumbens and striatum respectively.8. It is concluded that:(a) 3MT and DOPAC rates of formation provide better indices of DA release and metabolism than do their steady-state concentrations.(b) Some effects of DA uptake blockers on DA transmission, especially those of nomifensine and cocaine, may be attributed to increased DA release.(c) Patterns of regional effects of psychostimulants on the dynamics of DA release and metabolism may be better biochemical correlates of stimulant-induced behaviours than would changes in any single region.
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Affiliation(s)
- F Karoum
- Neuropsychiatry Branch, NIMH Neuroscience Center at St. Elizabeths, Washington, D.C. 20032
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26
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Izenwasser S, Terry P, Heller B, Witkin JM, Katz JL. Differential relationships among dopamine transporter affinities and stimulant potencies of various uptake inhibitors. Eur J Pharmacol 1994; 263:277-83. [PMID: 7843265 DOI: 10.1016/0014-2999(94)90723-4] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Binding to the dopamine transporter and inhibiting dopamine reuptake are considered important factors in regulating behavioral effects of cocaine. One prominent behavioral effect of cocaine and other dopamine uptake inhibitors is the stimulation of locomotor activity. To examine the relationship between action at the dopamine transporter and behavior, the displacement of [3H]WIN 35,428 (CFT naphthalene sulfate; 2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane-1,5-naphthalene disulfonate) binding in rat caudate putamen by cocaine and other uptake inhibitors was compared with stimulation of mouse locomotor activity. There was a significant correlation among affinities for binding and potencies for stimulating activity for cocaine and structurally similar compounds. For structurally dissimilar uptake inhibitors, however, there was no significant correlation among potencies for stimulation of activity and affinity for displacement of [3H]WIN 35,428 binding. These findings provide evidence that cocaine analogs may bind to the dopamine transporter in a manner that is fundamentally different from that for structurally dissimilar uptake inhibitors.
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Affiliation(s)
- S Izenwasser
- Psychobiology Section, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224
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27
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Boulay D, Leroux-Nicollet I, Duterte-Boucher D, Naudon L, Costentin J. Invariance of the density of dopamine uptake sites and dopamine metabolism in the rat brain after a chronic treatment with the dopamine uptake inhibitor GBR 12783. J Neural Transm (Vienna) 1994; 98:209-15. [PMID: 7748521 DOI: 10.1007/bf01276537] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
A chronic treatment (10 mg/kg, twice daily during 9 days) with the dopamine uptake inhibitor GBR 12783 was performed in rats at a dose increasing their locomotor activity. Forty-eight hours after the last administration, animals were sacrificed and 3H mazindol binding was performed on brain slices. Autoradiographic analysis revealed no change in this binding relatively to control animals in regions with high dopamine contents: striatum, nucleus accumbens, olfactory tubercle, substantia nigra and ventral tegmentum area. The treatment did not either modify the levels of dopamine (DA) and metabolites (HVA, DOPAC) both in the striatum and the nucleus accumbens. Thus, early after the end of the treatment, the chronic blockade of the dopamine uptake complex regulates neither the dopamine uptake complex nor the dopamine metabolism.
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Affiliation(s)
- D Boulay
- Unité de Neuropsychopharmacologie Expérimentale E. P. 76 du CNRS, Faculté de Médicine et de Pharmacie de Rouen, Saint Etienne du Rouvray, France
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28
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Dugast C, Suaud-Chagny MF, Gonon F. Continuous in vivo monitoring of evoked dopamine release in the rat nucleus accumbens by amperometry. Neuroscience 1994; 62:647-54. [PMID: 7870296 DOI: 10.1016/0306-4522(94)90466-9] [Citation(s) in RCA: 124] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The release of dopamine in the nucleus accumbens of anaesthetized rats was evoked either by electrical stimulation of the mesolimbic dopaminergic pathway or by local ejection of N-methyl-D-aspartate in the ventral tegmental area. Untreated carbon-fibre electrodes implanted in the nucleus accumbens were held at +400 mV versus a reference electrode, and the oxidation current was continuously monitored. Despite a poor selectivity to dopamine versus other oxidizable compounds such as ascorbic acid, the evoked responses were solely due to dopamine overflow in the extracellular fluid since they were closely correlated with the stimulations and exhibited all the expected characteristics related to a dopamine release. First, these effects were closely consistent with the anatomy of the mesolimbic dopaminergic system. Second, the responses to electrical stimulations were abolished by a tetrodotoxin ejection in the vicinity of the carbon-fibre electrode and they were strongly, but reversibly, diminished (60% decrease) when cadmium was substituted for calcium in an artificial cerebrospinal fluid ejected close to the electrode. Third, their maximal amplitudes were enhanced by amphetamine, pargyline, nomifensine and haloperidol. Fourth, inhibition of dopamine reuptake by nomifensine induced a five-fold decrease in the rate of decline of the evoked oxidation current. Fifth, contribution of noradrenaline and serotonin to the observed effects seems unlikely since specific reuptake blockers (desipramine and sertraline, respectively) did not alter them. Dopaminergic neurons discharge either in a single spike mode with a mean firing rate below 5 Hz or in a bursting pattern (intraburst frequency: 10 to 20 Hz).(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- C Dugast
- CNRS URA 1195, Centre Hospitalier Lyon-Sud, Pierre-Bénite, France
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29
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Tolliver BK, Carney JM. Comparison of cocaine and GBR 12935: effects on locomotor activity and stereotypy in two inbred mouse strains. Pharmacol Biochem Behav 1994; 48:733-9. [PMID: 7938129 DOI: 10.1016/0091-3057(94)90340-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The current study compares the acute and long-term effects of GBR 12935 and cocaine on locomotor activity and stereotypy in two genetically distinct strains of mice. Although cocaine stimulated locomotor activity maximally in both strains at 32 mg/kg, a single injection of cocaine stimulated locomotion to a greater degree in DBA/2J mice than in C57BL/6J mice. In contrast, GBR 12935 elevated locomotion to a greater extent in C57BL/6J mice at the maximally active dose of 10 mg/kg. The stimulant effects of cocaine diminished to near control levels in DBA/2J mice upon repeated injections, whereas cocaine-induced locomotion remained relatively consistent in C57BL/6J mice. Locomotor stimulation by GBR 12935 remained consistent in both strains with repeated injections. DBA/2J mice became sensitized to cocaine-induced stereotypy with repeated injections. Cocaine induced no stereotypy in C57BL/6J mice on any test day. No stereotypies were induced by GBR 12935 in either strain on any test day. Moreover, no cross-sensitization between cocaine and GBR 12935 was observed. These results demonstrate differences in the behavioral effects of two dopamine uptake inhibitors, and suggest that genetically controlled factors other than dopamine uptake inhibition contribute to the acute and adaptive behavioral responses to cocaine.
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Affiliation(s)
- B K Tolliver
- Department of Pharmacology, University of Kentucky College of Medicine, Lexington 40536
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